Apparatus for inserting a constantly oriented specimen chamber in a microanalyser



Feb. 4. 1969 .GUERNET 3,426,193

APPARATUS FOR INSERT A 00 TANTLY ORIENTED SPECIMEN NALYSER CHAMBER IN' ACROA FiledAJan. 19, 1965 Sheet of 2 Feb. 4,1969 I J. GUERNET 3,426,193

APPARATUS FOR INSERTING A CONSTANTLY ORIENTED SPECIMEN CHAMBER IN AMICROANALYSER Filed Jan. 19, 1965 Sheet 2 of 2 v am Mia [72W- By aifl fir MW United States Patent .0

US. Cl. 25049.5 Int. Cl. H01j 37/26 Claims ABSTRACT OF THE DISCLOSURE Anarrangement for inserting a specimen chamber in or removing it from anelectron beam microanalyser comprising a first arm supported forpivoting about and being translated along an axis parallel to the axisof the microanalyser, a support mounted in said arm slidably along adirection parallel to the axis of the microanalyser for supporting thespecimen chamber and a further arm pivotally mounted about an axisparallel to the last mentioned axes and carrying a finger engaging thesupport for determining with the first arm two opposite sides of aparallelogram so as to keep constant the orientation of the support.

The present invention relates to microanalysers and more particularly toan arrangement for inserting in or removing from a microanalyser thespecimen chamber, i.e. the enclosure in which the specimen is located.

In microanalysers, the surface of a sample is scanned by an electronbeam. This operation takes place in vacuum and it is advantageous toprovide a removable specimen chamber which can be, as a whole, insertedin, or removed from the microanalyser. The arrangement has to meet anumber of requirements: it has to be easy to handle, it must provideeasy access to the sample and to the body of the analyser, it has to beprovided with a closing system which ensures a seal for the vacuum, andit must permit easy and accurate positioning of the chamber in ahorizontal plane.

It is an object of the invention to provide a specimen chamberarrangement for a microanalyser which meets the above requirements.

According to the invention there is provided an arrangement forinserting a specimen chamber in, or removing it from an electron opticalanalyser, said arrangement comprising a support supporting said chamber,said support being mounted for pivoting about and being translated alongan axis parallel to the axis of said analyser, means being provided forkeeping contsant the orientation of said chamber in a plane while it isbeing pivoted.

For a better understanding of the invention and to show how the same maybe carried into effect, reference will be made to the drawingsaccompanying the following description and in which:

FIG. 1 is a schematic view in partial section of one embodiment of theinvention;

FIG. 2 shows, at an enlarged scale and in section in a plane differentfrom that of FIG. 1, a detail of the embodiment shown in that figure;and

FIG. 3 is a partially exploded view of the same arrangement.

FIG. 1 shows the table or stage 1 of a microanalyser on which thespecimen to be analysed is mounted. The table is placed in a metalenclosure or specimen chamber 2, which is kept under vacuum during use.Chamber 'ice 2 can be separated from the body 3 of the microanalyser.Chamber 2 includes, as shown in FIG. 2, a ring joint 4 and twocylindro-conical guiding fingers 20, which engage corresponding cavitiesin body 3 as shown in FIG. 2. Body 3 of the analyser is supported byfour columns 6 which rest on a sole 7.

A console 5 is, by means of a sleeve incorporated in its end, slidablymounted on one of columns 6 and can swing'about it. The free end ofconsole 5 is built as a cylindrical sleeve 23 into which is mounted acoaxial slider 12. A pivot 9, solid with a plate 8, is pivotally mountedin slider 12.

The orientation of plate 8 in a horizontal plane is kept constant bymeans of a finger 21, which engages a hole, formed in plate 8, and whoseopposite end pivots in one end of a rod 10, whose other end is pivotallymounted on a pivot 11 fixed to sole 7. The arm of console 5 and rod 10form the two opposite sides of a parallelogram, the axes of column 6, ofpivot 11, of finger 21 and of plate 8 defining, in the horizontal planedefined by these sides, the four corners of the parallelogram.

The top side of plate 8 carries three projections 25 for supportingenclosure 2 in a horizontal plane. In addition, it is provided with anaxial centring finger with a frustoconical end which engages a centralbore 19 in the base of enclosure 2, and a further finger 18 which fixesthe orientation of enclosure 2 with substantial accuracy.

Sleeve 23 is provided with two vertical, symmetrical slots through whichextends a pin 13 fixed to slider 12. The ends of pin 13 cooperate withcamming surfaces 22, shaped as portions of a helix, formed in a sleeve14 surrounding the lower part of sleeve 23. Sleeve 14 carries a lever15, which can be actuated by the operator.

Sleeve 14 rests on an elastic metal washer 17, carried by sleeve 23, anddesigned to limit the vertical stress that can be applied to plate 8through the camming surfaces 22, pin 13 and slider 12, when lever 15 isbeing actuated.

When the analyser is in the working position, sleeve 23 rests on atruncated cone 16, which forms projectibn on sole 7.

In the removal position of the enclosure 2, console 5 rests on sole 7and sleeve 23 is clear with respect to said sole.

The operation of the described arrangement, which is a particularexample of realisation of the invention, is as follows, assuming thatinitially the analyser is open, the removable enclosure 2 being in itsforward position.

In this position, the sleeve of console 5 rests on sole 7 and carriesthe whole of the mobile system.

Pin 13 rests on the lower end of surfaces 22. Enclosure 2 rests on thethree projections 25 of plate 8 and its position in the horizontal planeis defined by pivot 9 and finger 18.

In order to bring enclosure 2 to the operating position, the operatorrotates the mobile assembly about column 6. The parallelogram, definedby the arm of console 5 and by rod 10, distorts while leaving plate 8within its plane. Sleeve 23 runs against the truncated cone 16. Theoperator has then to push upwardly the mobile system to bring sleeve 23to rest on the truncated cone 16. At this instant, console 5 is slightlyclear of sole 7 and the Weight of the mobile assembly is carried by base1'6. A vertical force can then be applied along the analyser axis, whilethe reaction is directly absorbed by sole 7.

The rotary displacement of the mobile assembly is so limited by thecontact of console 5 with rod 10, that the axis of sleeve 23substantially coincides with the analyser axis.

The operator then actuates lever 15 and sleeve 14 presses against Washer17. Should some foreign body happen to be present between enclosure 2and body 3 of the analyser, washer 17 would somewhat damp the verticalstress to which the mobile assembly would be subjected.

While sleeve 14 is rotated, the camming surfaces 22 raise pin 13 andslider 12. Plate 8, which was resting against sleeve 23, is then raisedby slider 12. Enclosure 2 is raised with plate 8 and the guiding fingers20 engage the corresponding cavities in body 3, thus ensuring anaccurate positioning of enclosure 2. Ring seal 4 comes into contact withbody 3, the pressure exerted on seal 4 being uniformly distributed dueto the vertical thrust along the axis of enclosure 2. Ring seal 4ensures the necessary tightness to permit evacuation of the analyser,which is to be operated under vacuum. When the pressure drops inside theanalyser, the atmospreric pressure acts on enclosure 2, thus raising itand squeezing seal 4 until close contact is obtained between theopposite metal surfaces of body 3 and enclosure 2, so ensuring a sealfor a high vacuum.

The removal of the sample holder enclosure is effected in the samemanner, the steps of the operation taking place in the reverse order.

Admitting air in the analyser allows enclosure 2 to be lowered on plate8 due to its own weight and the action of the ring joint 4. Rotatinglever 15 lowers slider 12 and plate 8, while seal 4 becomes completelyclear of body 3 and positioning fingers 20 disengage therefrom.

The operator can then pull the mobile assembly towards him. Sleeve 23 ismoved away from plate 16. Console 5 then rests on sole 7 and pivotsabout column 6. During the rotation, plate 8 and enclosure 2 have acircular motion of translation in the horizontal plane by virtue of theparallelogram formed by the arms of console 5 and rod 10.

The specimen chamber arrangement according to the invention possessesseveral advantages.

It provides a total clearance, at the sealing joint, between the lowerside of the analyser and the upper side of the specimen chamber, thusensuring easy access to the body of the analyser and to the sample underexamination. The movable assembly is axially supported, the stressesbeing thus better distributed during the closing operation.

An approximate centring of the sample chamber is ensured due to the factthat the displacement of the movable assembly is limited by theparallelogram system. An accurate centring of the sample chamber isensured by two locating fingers. Also, the sample chamber is constantlykept in the same horizontal plane.

Of course, the invention is not limited to the embodiment described andshown which has been given solely by way of example.

What I claim is:

1. An arrangement for inserting a specimen chamber in or removing itfrom an electron beam microanalyser system having an axis, saidarrangement comprising: an arm having a first and a second end; firstmeans for supporting said arm, at said first end, pivotally about andslidably along a further axis, parallel to said axis and at a distancefrom said axis equal to the length of said arm; a support for supportingsaid chamber; second means for mounting said support at said second endof said arm slidably along a direction parallel to said axes; thirdmeans for keeping constant the orientation of said support in a planenormal to said axes during the rota tion of said arm; and fourth meansfor pivoting said arm about said further axis and for displacing saidarm and said support in a direction parallel to said axes; said thirdmeans comprising a further arm having a first and a second end and thesame length as said arm, fifth means for supporting said further arm, atsaid first end thereof, pivotally about an axis parallel to said axesand a finger carried by said second end of said further arm and engagingsaid support at a distance from said second end of said arm equal to thedistance between said firsts ends respectively of said arm and saidfurther arm.

2. An arrangement as claimed in claim 1, wherein said support is atable, said second means comprise a slider slidably mounted at saidsecond end of said arm, said slider having a first and a second end,said first r end of said slider engaging said table, and said fourthmeans comprise camming means associated with said second end of saidslider for the displacement of said slider and said arm parallel to saidaxes and a lever associated with said camming means for pivoting saidarm about said further axis and for controlling said camming means.

3. An arrangement as claimed in claim 2, wherein said first meanscomprise: a base; and a first column mounted on said base, said columnextending along said further axis and said first end of said arm beingpivotally and slidably mounted on said first column.

4. An arrangement as claimed in claim 3, wherein said fifth meanscomprise a further column parallel to said first column and mounted onsaid base.

5. An arrangement for inserting a specimem chamber in or removing itfrom an electron beam micronanalyser system, said system having anopening, said opening having an axis, said arrangement comprising: abase; a first column mounted on said base, said column being parallel tosaid axis and at a predetermined distance from said axis; an arm havingtwo ends and a length equal to said predetermined distance, one of saidends being pivotally and slidably mounted on said first column; a tablesupporting said chamber; a slider mounted in said second end of said armslidably along a direction parallel to said axis, said slider having afirst and a second end, said first end engaging said table; cammingmeans associated with said second end of said slider for thedisplacement thereof parallel to said axis; a lever associated with saidcamming means for pivoting said arm about said first column and forcontrolling said camming means; .a further column parallel to said firstcolumn and mounted on said base; a further arm having a first and asecond end and the same length as said arm, said first end of saidfurther arm being pivotally supported about said further column; afinger carried by said second end of said further arm and engaging saidtable at a distance from the axis of said slider equal to the distancebetween said column and said further column for preventing any change inthe orientation of said table in a plane normal to said axis during therotation of said arm; said chamber having an open top and means forproviding a seal between said open top and said opening upon translationof said chamber along said direction; and a projection on said base,coaxial with said opening, said projection having sloping edges.

References Cited UNITED STATES PATENTS WILLIAM F. LINDQUIST PrimaryExaminer.

